arXiv subjects

Kakoli Bera

Publications and source records attributed to Kakoli Bera.

3 recordsLinked to original sources

arXiv2022

Fledgling quantum spin Hall effect in pseudo gap phase of Bi2212

We study the emergence of the quantum spin Hall (QSH) states for the pseudo-gap (PG) phase of Bi2212 bilayer system, assumed to be D-density wave(DDW) ordered, starting with a strong Rashba spin-orbit coupling(SOC) armed, and the time reversal symmetry (TRS) complaint Bloch Hamiltonian. The presence of strong SOC gives rise to non-trivial, spin-momentum locked spin texture tunable by electric field. The emergence of quantum anomalous Hall effect with TRS broken Chiral DDW Hamiltonian of Das Sarma et al. is found to be possible.

cond-mat.mes-hall↗

arXiv2021

Chiral d density wave ordered pseudo gap phase of Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ bilayer. Spin texture and Dzyaloshinskii Moriya interaction

We model Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ (Bi2212) bilayer system by an inversion symmetry broken and time reversal non invariant Bloch Hamiltonian H. The pseudo-gap phase of the bilayer is assumed to be chiral d density wave ordered. The focal point of the paper is the theoretical study of the spin momentum locking (SML), due to the presence of a strong spin orbit coupling in Bi2212, reported earlier in this phase in a spin and angle resolved photoemission spectroscopic measurement. The non trivial spin texture in k space is found tunable by electric field and also by intercalation.The Dzyaloshinskii Moriya interaction (DMI) coefficient, where DMI being important energy for chiral textures like magnetic skyrmions, are calculated to set the stage for detailed studies in a sequel. We also find that,in the nodal region, in the presence of Zeeman field B , as in a s wave superconductor, for B greater than or equal to B_c (a critical value) a vortex in this system becomes a non-Abelian anyon with a Majorana zero mode required for the fault tolerant quantum computation.

cond-mat.supr-con↗

arXiv2021

On strong f-electron localization effect in topological kondo insulator

We study strong f-electron localization effect on surface state of a generic topological Kondo insulator (TKI) system by performing a mean-field theoretic (MFT) calculation within the frame-work of periodic Anderson model (PAM) using slave-boson technique. The surface metallicity together with bulk insulation is found to require this type of localization. A key distinction between surface states in a conventional insulator and a topological insulator is that, along a course joining two time-reversal invariant momenta (TRIM) in the same BZ, there will be intersection of these surface states, even/odd number of times, with the Fermi energy inside the spectral gap. For even (odd) number of surface state crossings, the surface states are topologically trivial (non-trivial). The symmetry consideration and the pictorial representation of surface band structure obtained here show odd number of crossing leading to the conclusion that, at least within PAM framework, the generic system is a strong topological insulator.

cond-mat.str-el↗